US6485072B1 - Bumper system for motor vehicles - Google Patents

Abstract

A bumper system for a motor vehicle includes an energy absorber and a bumper beam connected to the energy absorber and for connection to vehicle structure and having a general B shape. The bumper system also includes a member disposed between the bumper beam and a rail of the motor vehicle to absorb energy during an impact with an object by the bumper system.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from provisional application Serial No. 60/170,935, filed Dec. 15, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to bumpers for motor vehicles and, more specifically, to a bumper system for a motor vehicle.

2. Description of the Related Art

It is known to provide a bumper system for a front end or rear end of a motor vehicle. For a front end of the motor vehicle, the bumper system typically includes a bumper beam extending transversely and secured to a forward end of a pair of front rails, which extend longitudinally and are spaced transversely. The bumper system also includes an energy absorber extending transversely and secured to the bumper beam. The bumper system may include a fascia disposed over and covering the energy absorber.

It is also known that the bumper system protects a body of the motor vehicle from low speed impact with an object through elastic or semi-plastic deformation of the energy absorber. It is further known that the bumper system is an absorber for high-speed impact with an object through major plastic deformation of the bumper beam. It is yet further known that bumper beams of bumper systems tend to buckle at a centerline in an uncontrolled fashion during low and highspeed impacts.

Although the above bumper system has worked, it suffers from the disadvantage that the bumper beam has a constant cross-section which is either too weak to resist low speed impact at a center thereof or makes it too strong to absorb impact energy before the supporting vehicle rails collapse under the motor vehicle. As a result, it is desirable to provide a bumper system having a bumper beam which will better balance both low speed impact protection and high speed energy absorption for a bumper system of a motor vehicle. It is also desirable to provide a reinforcement for a bumper beam that reduces damage to the bumper beam at low speed impacts but allows the bumper beam to crush at high-speed impacts. It is further desirable to provide a metal device positioned behind or inside a bumper beam that when impacted crushes with an efficient and effective energy curve. Therefore, there is a need in the art to provide a bumper system that meets these desires.

SUMMARY OF THE INVENTION

Accordingly, the present invention is a bumper system for a motor vehicle. The bumper system includes an energy absorber and a bumper beam connected to the energy absorber and for connection to vehicle structure and having a general B shape. The bumper system also includes a member disposed between the bumper beam and a rail of the motor vehicle to absorb energy during an impact with an object by the bumper system.

One advantage of the present invention is that a new bumper system is provided for a motor vehicle. Another advantage of the present invention is that the bumper system includes a bumper beam made from a manufacturing process such as a roll formed process or an extrusion process with a generally “B” shaped cross-section which balances both low-speed impact and high-speed impact of the motor vehicle. Yet another advantage of the present invention is that the bumper system has a reinforcement attached to a “B” shaped bumper beam that reduces damage to the bumper beam at a low speed impact but allows the bumper beam to crush at a high-speed impact. Still another advantage of the present invention is that the bumper system includes a centerline bumper reinforcement of unique cross-sectional geometry, allowing the bumper beam to crush at high speed yet resist low speed damage. A further advantage of the present invention is that the bumper beam reinforcement resists excessive centerline bending deformation. Yet a further advantage of the present invention is that the bumper system includes a metal device is positioned behind or inside a vehicle bumper beam that when impacted crushes with an efficient and effective energy curve. Still a further advantage of the present invention is that the metal device is relatively low cost to manufacture compared to more expensive hydraulic strut assemblies. Another advantage of the present invention is that the metal device has a unique geometry and simplicity and crushes in a very efficient manner. Yet another advantage of the present invention is that the metal device reduces cost during repair of a vehicle after an incidental collision. Still another advantage of the present invention is that the metal device is low cost to manufacture, lighter than traditional strut designs, low cost to assembly and service in the field, very efficient crush characteristics (square load-deflection curve), ease of design flexibility for different vehicles, ease of design to commonize part between vehicles, greatly reduces the cost to repair, and offers a controlled joint to bumper beam which allows for improved high speed energy management with lower intrusion into an occupant compartment of the vehicle.

Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a bumper system, according to the present invention, illustrated in operational relationship with a motor vehicle.

FIG. 2 is an exploded perspective view of the bumper system of FIG.1.

FIG. 3 is a sectional view taken alongline3—3 of FIG.1.

FIG. 4 is an exploded elevational view of a bumper beam and reinforcement of the bumper system of FIG.1.

FIG. 5 is an elevational view of a bumper beam and reinforcement of the bumper system of FIG.1.

FIG. 6 is a view similar to FIG. 5 illustrating a deformed stage.

FIG. 7 is a fragmentary elevational view of another embodiment, according to the present invention, of the bumper system of FIG.1.

FIG. 8 is a perspective view of a device of the bumper system of FIG.7.

FIG. 9 is a side elevational view of the device of the bumper system of FIG.7.

FIG. 10 is a plan view of the device of the bumper system of FIG.7.

FIG. 11 is a fragmentary plan view of the bumper system of FIG. 7 illustrating a first stage of a high-speed impact.

FIG. 12 is a view similar to FIG. 11 illustrating a second stage of a high-speed impact.

FIG. 13 is a view similar to FIG. 11 illustrating a third stage of a high-speed impact.

FIG. 14 is a view similar to FIG. 11 illustrating a fourth stage of a high-speed impact.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring to the drawings and in particular FIG. 1, one embodiment of abumper system10, according to the present invention, is illustrated in operational relationship with a motor vehicle, generally indicated at12. Thebumper system10 is disposed at a front or forward end of themotor vehicle12. It should be appreciated that thebumper system10 may be disposed at a rear or rearward end of themotor vehicle12. It should also be appreciated that, except for thebumper system10, themotor vehicle12 is conventional and known in the art.

As illustrated in FIGS. 2 through 6, thebumper system10 includes a bumper beam, generally indicated at16. Thebumper beam16 extends laterally and is secured to aforward end17 of a pair offront rails18 by suitable means such as welding or mechanical fastening. Thebumper beam16 is a hollow member having a general “B” cross-sectional shape. Thebumper beam16 has a front orimpact wall20 extending generally vertically and laterally. Thebumper beam16 also has an upper ortop wall22 and a lower orbottom wall24 inclined longitudinally from theimpact wall20 and extending laterally. Thebumper beam16 has a curved or arcuateforward corner wall26 interconnecting theimpact wall20 and the upper andlower walls22 and24. Thebumper beam16 also has a rear or supportingwall28 extending generally vertically and laterally from the upper andlower walls22 and24. Thebumper beam16 has a curved or arcuaterear corner wall30 interconnecting the supportingwall28 and the upper andlower walls22 and24. It should be appreciated that theimpact wall20 has a height greater than the supportingwall28.

Thebumper beam16 also has a plurality of, preferably two generally horizontalinterior walls32 extending laterally and longitudinally forward toward theimpact wall20. Thebumper beam16 has a curved or arcuateinner corner wall34 interconnecting theinterior walls32 and supportingwall28. Thebumper beam16 has aninclined transition wall36 extending laterally and longitudinally forward from theinterior walls32 and toward a center of theimpact wall20 and a curved orarcuate projection wall38 interconnecting the ends of thetransition walls36. Theimpact wall20 is formed as two portions with each portion extending from thefront corner walls26 and spaced vertically from each other to form agap40 therebetween. Theprojection wall38 is secured to the upper and lower portions of theimpact wall20 by suitable means such as welding or mechanical fastening to increase a stability of thebumper beam16 against a “match boxing” behavior. The upper and lower portions of theimpact wall20 have a plurality ofapertures42 extending therethrough and spaced laterally for a function to be described.

As illustrated in FIG. 3, a top wall of therail18 is located vertically between theupper wall22 and the topinterior wall32 of thebumper beam16 and a lower wall of therail18 is located vertically between thelower wall24 and the lowerinterior wall32 of thebumper beam16 in a symmetrical manner. As a result, the stiffness of therail18 causes the twointerior walls32 to collapse prior to the upper andlower walls22 and24 collapse. It should be appreciated that this overlapping collapse assures a uniform energy absorption characteristic in high-speed impacts. It should also be appreciated that thewalls22,24, and32 may have a plurality of apertures (not shown) extending therethrough to achieve a desired crush stiffness of thebumper beam16.

Thebumper beam16 is made of a relatively rigid material such as metal. Thebumper beam16 is integral, unitary, and formed as one-piece by manufacturing processes such as roll forming which a conventional process known in the art. It should also be appreciated that other manufacturing processes such as extruding and stamping may be used to form thebumper beam16. It should also be appreciated that thebumper beam16 may be attached to a rearward end (not shown) of a pair of rear rails (not shown) of themotor vehicle12 by suitable means such as welding.

Thebumper system10 includes anenergy absorber44. Theenergy absorber44 extends laterally and is secured to thebumper beam16. Theenergy absorber44 has a plurality ofprojections46 extending rearward therefrom and through theapertures42 in theimpact wall20. Theenergy absorber44 is a solid member having a generally trapezoidal shape with rear upper and lower lips48 and SO extending rearward. The upper andlower lips48 and50 have a generally arcuate or curved shape to extend over thefront corner walls26 of thebumper beam16. Theenergy absorber44 is made of a relatively deformable material such as foam. Thebumper beam16 may have a horizontal sweep to reduce the depth of the deformable material of theenergy absorber44. It should be appreciated that theapertures42 in theimpact wall20 allow theenergy absorber44 to have local penetration in order to avoid excess compacting of the deformable material during a high-speed impact with an object (not shown).

Thebumper system10 further includes afascia50 extending laterally and vertically to cover theenergy absorber44. Thefascia50 is secured to vehicle structure (not shown) by suitable means such as fasteners (not shown). Thefascia50 is made of a relatively rigid material such as plastic. It should be appreciated that thefascia50 is conventional and known in the art.

Thebumper system10 also includes areinforcement52 disposed between therails18 and thebumper beam16 to resist excessive centerline bending deformation and improve global stiffness of thebumper beam16. Thereinforcement52 has a rear orbase wall54 extending generally vertically and laterally. Thereinforcement52 also has a plurality of, preferably two generallyhorizontal side walls56 extending laterally and longitudinally forward from thebase wall54. Thereinforcement52 has a curved orarcuate corner wall58 interconnecting theside walls56 and thebase wall54. Thereinforcement52 has aninclined transition wall60 extending laterally and longitudinally forward from theside walls56 and a curved orarcuate projection wall62 interconnecting the ends of thetransition walls60. Thereinforcement52 is made of a metal material such as steel and is formed as a one-piece stamping by a stamping process, which is conventional and known in the art Thereinforcement52 has thebase wall54 secured to the upper and lower portions of therails18 by suitable mean such as welding. Thereinforcement52 also has theprojection wall62 disposed adjacent theprojection wall38, thetransition walls60 disposed adjacent thetransition walls36, theside walls56 disposed adjacent theinterior walls32, and thebase wall54 adjacent the supportingwall28 and secured thereto by suitable means such as welding. Thereinforcement52 is a monolithic structure being integral, unitary, and one-piece.

In operation, thebumper system10 has a first stage or mode. In the first mode at low speeds (i.e., less than or equal to approximately ten miles per hour), thebumper system10 impacts an object such as a wall. Theenergy absorber44 is deformed and absorbs the energy of the impact without deforming thebumper beam16. In this case, theenergy absorber44 is compressed longitudinally and expands vertically to absorb the impact energy and the slower impact speed will not have a tendency to deform or collapse thebumper beam16. As illustrated in FIG. 6, thereinforcement52 allows thebumper beam16 to elastically twist or bend without a permanent dent in thebumper beam16, thereby preventing replacement of thebumper beam16.

Thebumper system10 has a second stage or mode. In the second mode at high speeds (i.e., greater than approximately ten miles per hour), thebumper system10 impacts an object such as the wall and thereinforcement52 allows thebumper beam16 to crush at centerline and limit intrusion into an occupant compartment of thevehicle12. The twointerior walls32 initiate first stage plastic hinge points around thecorner walls34 to deform thewalls32 partially due to its geometry and partially due to the partial supporting of the vehicle structure such as therail18. The deformable material of theenergy absorber44 will be locally extruded into the hollow interior of thebumper beam16 through theapertures42 in theimpact wall20. The upper andlower walls22 and24 initiate second stage plastic hinge points around thecorner walls26 to deform the upper andlower walls22 and24 of thebumper beam16. Thebumper beam16 will finally go into its compact stage by total deformation of all generallyhorizontal walls22,24, and32. It should be appreciated that thereinforcement52 allows thebumper system10 to absorb more energy than traditional designs that hold their shape and transfer energy to other structure of thevehicle12. It should also be appreciated that thereinforcement52 has less of a plan view arch shape or sweep than thebumper beam16 itself, thereby allowing thereinforcement52 to be made of less formable yet higher strength lower thickness steel which saves vehicle weight. It should further be appreciated that thereinforcement52 reduces the moment or non-axial forces on thebumper beam16 foundation points and acts as a “tie bar” or two-force member sharing the forces of the impact rather than allowing concentration of stresses at the bumper beam mounting points.

Referring to FIGS. 7 through 10, anotherembodiment110, according to the present invention, of thebumper system10 is shown. Like parts of thebumper system10 have like reference numerals increased by one hundred (100). In this embodiment illustrated in FIG. 7, thebumper system110 eliminates thereinforcement52 described above and incorporates an energy absorbing member ordevice170. Theenergy absorbing device170 efficiently absorbs energy after thebumper beam116 has collapsed, in turn, protecting the frame and structure of thevehicle12, which is expensive to repair. Theenergy absorbing device170 has a supportingwall172 andside walls174 extending from the supportingwall172 to form a box-like cross-section. Theenergy absorbing device170 also has inclinedtransition walls176 extending from theside walls174 to anend wall178 to form a closed section. Theend wall178 is inclined relative to a plane parallel to the supportingwall172. Theenergy absorbing device170 may includefirst apertures180 extending through theside walls174 and/orsecond apertures182 through theend wall178. Theenergy absorbing device170 is made of a metal material such as steel and is integral, unitary, and formed as a one-piece stamping by a stamping process, which is conventional and known in the art. Theenergy absorbing device170 is secured to an end of therails18 by suitable means such asfasteners184 extending through the supportingwall172 and a wall of theforward end17 of therails18. The operation of thebumper beam116 is similar to thebumper beam16.

In operation, thebumper system10 has a first stage or mode as illustrated in FIGS. 11 and 12. In the first mode at low speeds (i.e., less than or equal to approximately ten miles per hour), thebumper system110 impacts an object such as awall186. Theenergy absorber144 is deformed and absorbs the energy of the impact without deforming thebumper beam116. In this case, theenergy absorber144 is compressed longitudinally and expands vertically to absorb the impact energy and the slower impact speed will not have a tendency to deform or collapse thebumper beam116.

Referring to FIGS. 12 and 14, thebumper system110 has a second stage or mode as illustrated. In the second mode at high speeds (i.e., greater than approximately ten miles per hour), thebumper system110 impacts an object such as thewall186. After thebumper beam116 finally go into its compact stage by total deformation, theenergy absorbing device170 undergoes deformation. The twoside walls174 initiate first stage plastic hinge points around thecorner walls175 to deform theside walls174 partially due to its geometry and partially due to the partial supporting of the vehicle structure such as therail18. Thetransition walls176 initiate second stage plastic hinge points around the corners thereof to deform thetransition walls176 of theenergy absorbing device170 as illustrated in FIG.13. Theenergy absorbing device170 finally goes into its compact stage by total deformation of all thewalls172,174,176, and178 as illustrated in FIG.14.

The present invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation.

Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.

Claims (12)

What is claimed is:

1. A bumper system for a motor vehicle comprising:

an energy absorber; and

a bumper beam connected to said energy absorber and adapted for connection to vehicle structure and having a general B shape, said bumper beam having a front wall connected to said energy absorber and a rear wall adapted for connection to the vehicle structure and a projection extending from said rear wall toward said front wall to form a channel therein; and

a member comprising a reinforcement having a portion extending longitudinally and being at least partially disposed within said channel of said bumper beam, said reinforcement being located between said bumper beam and a rail of the motor vehicle to absorb energy during an impact with an object by said bumper system.

2. A bumper system as set forth inclaim 1 wherein said reinforcement has a base wall extending vertically and laterally.

3. A bumper system as set forth inclaim 2 wherein said reinforcement has a plurality of side walls extending generally perpendicularly from said base wall and spaced from each other.

4. A bumper system as set forth inclaim 3 wherein said reinforcement has a transition wall extending from said side walls toward each other.

5. A bumper system as set forth inclaim 4 wherein said reinforcement has a projection wall being arcuate in shape and interconnecting said transition walls.

6. A bumper system as set forth inclaim 1 wherein said reinforcement is made of a metal material.

7. A bumper system as set forth inclaim 1 wherein said reinforcement is secured to said bumper beam and adapted to be secured to the rail by either one of welds or mechanical fasteners.

8. A bumper system as set forth inclaim 1 wherein said bumper beam is integral, unitary, and formed as one-piece.

9. A bumper system for a motor vehicle comprising:

an energy absorber;

a bumper beam interconnecting said energy absorber and vehicle structure and having a general B shape, said bumper beam having a front wall connected to said energy absorber and a rear wall adapted for connection to the vehicle structure and a projection extending from said rear wall toward said front wall to form a channel therein; and

a reinforcement having a portion disposed in said channel of said bumper beam, said reinforcement being located between said bumper beam and a rail of the motor vehicle to absorb energy during an impact with an object by said bumper system.

10. A bumper system as set forth inclaim 9 wherein said reinforcement has a base wall extending vertically and laterally.

11. A bumper system as set forth inclaim 10 wherein said reinforcement has a plurality of side walls extending generally perpendicularly from said base wall and spaced from each other.

12. A bumper system as set forth inclaim 11 wherein said reinforcement has a transition wall extending from said side walls inwardly toward each other and a projection wall being arcuate in shape and interconnecting said transition walls.

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